Lighting system



FIG. 1 illustrates a perspective view of the design for a lighting system;

FIG. 2 illustrates a front view of the embodiment set forth in FIG. 1; and,

FIG. 3 illustrates a side view of the embodiment set forth in FIG. 1.

The broken lines in the drawings illustrate portions of the lighting system which form no part of the claimed design. 

CLAIM The ornamental design for a lighting system, as shown and described. 